<template>
  <div class="slider" ref='slider'>
    <div class='slider-group' ref='sliderGroup'>
      <slot>
      </slot>
    </div>
    <div class='dots'>
      <span
        class='dot'
        v-for='(item,index) in dots' :key='index'
        :class="{active:currentPageIndex===index}"></span>
    </div>
  </div>
</template>

<script>
import BScroll from 'better-scroll'
import { addClass } from 'common/js/dom'

export default {
  name: '',
  components: {},
  data() {
    return {
      dots: [],
      currentPageIndex: 0,
    }
  },
  props: {
    loop: {
      type: Boolean,
      default: true,
    },
    autoPlay: {
      type: Boolean,
      default: true,
    },
    interval: {
      type: Number,
      default: 4000,
    },
  },
  watch: {},
  methods: {
    _setSliderWidth() {
      this.children = this.$refs.sliderGroup.children
      let width = 0
      let sliderWidth = this.$refs.slider.clientWidth
      for (let i = 0; i < this.children.length; i++) {
        let child = this.children[i]
        addClass(child, 'slider-item')
        child.style.width = sliderWidth + 'px'
        width += sliderWidth
      }

      if (this.loop) {
      }
      this.$refs.sliderGroup.style.width = width + 'px'
    },
    _initSlider() {
      this.slider = new BScroll(this.$refs.slider, {
        scrollX: true,
        scrollY: false,
        momentum: false,
        click: true,
        snap: {
          loop: this.loop,
          snapThreshold: 0.3,
          snapSpeed: 400,
        },
      })

      this.slider.on('scrollEnd', () => {
        let pageIndex = this.slider.getCurrentPage().pageX
        this.currentPageIndex = pageIndex

        if (this.autoPlay){
          clearTimeout(this.timer)
          this._play()
        }
      })
    },
    _initDots() {
      let length = this.children.length
      if (this.loop) {
        length -= 2
      }
      this.dots = new Array(length)
    },
    _play() {
      this.timer = setTimeout(() => {
        this.slider.next()
      }, this.interval)
    },
  },
  computed: {},
  created() {
  },
  mounted() {
    this.$nextTick(() => {
      this._initSlider()
      this._setSliderWidth()
      this._initDots()

      if (this.autoPlay) {
        this._play()
      }
      window.addEventListener('resize',()=>{
        if (!this.slider) {
          return
        }
        console.log('resize')
        this._setSliderWidth()
      })
    })
  },
  activated() {
    if (this.autoPlay) {
      this._play()
    }
  },
  deactivated() {
    clearTimeout(this.timer)
  },
  beforeDestroy() {
    clearTimeout(this.timer)
  },
}
</script>

<style lang="stylus" scoped>
  @import "~common/stylus/variable"
  .slider
    /*height 0*/
    /*padding-top calc(30%)*/
    position relative
    .slider-group
      overflow hidden
      white-space nowrap
      font-size 0
      .slider-item
        background red
        display inline-block
        /*float left*/
        box-sizing border-box
        /*overflow hidden*/
        text-align center
        a
          display block
          width 100%
          overflow hidden
          text-decoration none
        img
          display block
          width 100%
    .dots
      position absolute
      right 0
      left 0
      bottom 12px
      text-align center
      font-size 0
      .dot
        display: inline-block
        margin: 0 4px
        width: 8px
        height: 8px
        border-radius: 50%
        background: $color-text-l
        &.active
          width: 20px
          border-radius: 5px
          background: $color-text-ll
</style>
